I am looking for a freeware (I'll even go shareware if necessary) program that allows you to design the trajectory of a spacecraft. The software needs to support gravity assists, satellite systems (meaning it would allow for designs say around Jupiter, with gravity assists at the various moons), and for inputing dry and wet mass at launch and the specifics of the launch vehicle. Preferably, but not required, it would support either NAIF kernels or support a launch at some day in the future with the appropriate planetary and satellite positions.

Oh, and preferably, it works on Windows machines, but UNIX/Solaris and Macs are fine.

Phone directory : Seal, D



On a serious note - I've looked for something similar in the past purely for fun and not come across anything really.

Doug

If it doesn't already exist, it would be fun to work on, I think. I've been playing around with writing code for trajectory calculations on an ad-hoc basis, but something such as you describe definitely sounds cool.

Does it have to be so good that you could actually use it for a real spacecraft? And would you want cool graphics, or would you settle for hard, cold numbers?

--Greg

The software I would like to find does not have to create really cool graphics, but should be able to export to a format Celestia can read so I can create the really cool graphics there. The idea I have in mind is to create a basic Jovian system tour mission with repeated Io flybys (1 flyby/month), then use Celestia to simulate the kind of coverage would be obtained on each encounter.

Have you seen this site?

The Matlab stuff is cool, but it's not real-world; to make a real-world simulation work, I think you'd minimally need to start with the data from a real ephemeris (such as JPL has) so at least the large bodies are always correctly positioned and then do a numerical simulation of all the small bodies that you actually care about.

None of those programs quite seems to do this, but this one comes the closest:

http://www.cdeagle.com/aa_cm/cae2ho.pdf

The need to do burns with different launch vehicles also adds complexity, but this one seems to handle it:

http://www.cdeagle.com/aa_cm/NASA_CR-1430.pdf

plus I have some books on it -- it's not rocket science. (Wait . . .)

NAIF kernels don't look hard to handle, although I'm wondering what you'd need them for if you already had an ephemeris.

--Greg

I'm a little surprised that such tools aren't readily available in a big university's planetary sciences department. Or at least that the folks in the engineering department don't let the planetary sciences people use their facilities. Do JPL and JHUAPL use only proprietary software to plan their missions?

TTT (looking forward to the cool graphics!)

JPL uses in-house tools as far as I know. Recently some projects have started using SOAP (from Aerospace Corp) but I don't know what licensing terms it has or what it can do in this area (I've mostly seen it used for visualization.) I've worked on proposals where we used STK's Astrogator (costs big, big bucks). SAIC's Trajectory Optimizer used to come in a cheap demo version that was sufficient to compute delta-v for planetary transfers of various sorts, but I don't see it on the net any more.

I think it's unlikely that a truly usable package that does all this stuff exists for free.

I'm still a little fuzzy on the complete set of functional requirements. VP said "trajectory design," but I'm not 100% sure what all that entails.

For example, assume I just wanted to plan a trajectory to a planet. I can see the following scenarios:

1) I have a minimum payload and I want the cheapest rocket that can get it there directly.
1a) Given that there are only so many rockets, an exact match is unlikely, so how much additional mass can it carry?
1b) Or how much time can I shave off the trip?
1c) Is it any cheaper to get an assist off a specific other planet?
1d) What's the scenario if I need to get into orbit?
2e) What if I can do aerobraking?

2) List the available launch windows for the next decade
2a) List the next N launch windows
2b) Given I had extra lift (see 1b) how wide can I make my launch window?

3) For gravitational assists,
3a) If I pick the bodies and the order to visit them, is there a route that needs no exra fuel?
3b) If so, when's the next launch window?
3c) If not, can we burn extra fuel along the way and make it work?
3d) What's the best combination of boost and bodies, given an N-year timetable?

4) Miscellaneous
4a) Include factors for air resistance leaving Earth
4b) Include ion propulsion, not just "fast" burns.
4c) Include solar sail

That's all I can think of -- some of these are much harder than others. (3d is probably the worst). Others look ideal for an academic open-source project. I should ask if UW has anything like it.

Still missing is use cases for this; exactly how would the system support these features? Would the user edit a configuration file to specify where he/she wanted to go and when, or would it involve clicking on objects in a solar-system map?

--Greg

Tony Dunn's Gravity simulator meets some of your requirements. I appears to be intended to be good enough to model the type of things you are looking for and it can be set up with JPL Horizons ephemeris data to set initial conditions. I'm not sure if it can handle the sort of sequencing that a trajectory planner would need but it might be worth a look. It's freeware but not open source.

Since the LV's are propriety, the companies don't release all the necessary info for accurate modeling and mission design.

And there is the spectre of ITAR

Whenever a real mission is launched, we know it weighed on the pad and what it was loaded with, and we know the orbital parameters of the payload a day or so later, correct? That places contraints on what those hidden variables can be, so, without knowing exactly what part of the equation we're talking about, I'd expect that any vehicle that has been used for five or more launches can almost certainly be modeled well enough for our purposes. I'd probably see if I could apply Expectation Maximization to it, if I were doing this for real.

Since all the information we're talking about is already in the public domain, I don't see how ITAR applies. That doesn't mean some bureaucrat might not try to apply it anyway, but it wouldn't be in my list of top 10 concerns.

--Greg

Helvick: That's a GREAT site! And, I agree, it handles a lot of the hard stuff. Perhaps we really CAN do this with public software glued together with Perl scripts. :-)

--Greg

Not directly related to volcanopele's requests, but here's a site that has some free downloads : http://www.jaqar.com/. Take note of the Swing-by Calculator for example, it can find and optimize interplanetary transfers. The free version used to be limited, but you could have sent a mail to JAQAR back in the day to get a sort of a free student licence to unlock the full feature set.

That one is even more impressive. It would appear that the only thing Jaqar is missing is details of the launch itself. Since it supports automation, that means it can be called from another program (they give Excel VBA as an example), so any other features could be built on top of it.

Volcanopele: How much of what you need is missing from the free download from jaqar?

--Greg

ITAR applies to a lot of previously publicly availabe technical details - It is possible to find stuff in engineering libraries that cannot be posted on the internet or discussed with 'aliens'. Trajectory software falls into a broad category protected engineering. While it would not likely violate the rules for someone to share this type of software with VP, it may be a violation to post it on the internet, or if VP passed it on to the wrong visitor to Disneyland. (I cannot share the software I have access to because of licensing issues.)

But ITAR only applies to US citizens, so it would only be a violation for the creator of the program if he was a US citizen, and he posted it on the net, or for that matter, if a US citizen posted the work of a US citizen relating to it. It's not an ITAR violation (I think...) to merely point someone to a program that already exists on the internet.

I'll bet they're less strict about software that doesn't even exist. If not, I think I want to talk to my Congressman. :-)

--Greg

Creating it and then posting it would be a violation

Jim: Given your handle and lack of a disclaimer, it sounds like you're representing the NSF's official position here. If that's the case, you'll have to provide a last name before I'll believe it.

--Greg

"NSF" apparently refers to nasaspaceflight.com, not to the National Science Foundation. I don't think Jim is being official here, just very terse.

That said, ITAR is a real concern for this sort of thing. Trying to get launch vehicle information beyond that given in the cleared payload planning guides is going to be pretty hard, if not impossible.

Interestingly I've just found out that ITAR covers the Export or Import of proscribed "Significant Military Equipment".

Section 121.8 is pretty clear in stating that software is only specifically proscribed if it is enumerated in section 121.1 and Trajectory planning software systems are arguably not covered by any of the specifically proscribed technology areas however the final space systems section has a wonderful catch all at the end:

"Further, technical data directly related to the manufacture or production of all spacecraft, notwithstanding the nature of the intended end use (e.g., even where the hardware is not SME), is designated SME."

So it's not just that US folks are prevented from sharing material with the rest of the world, ITAR cuts both ways and it would be a breach of ITAR for any US citizen to download and use Jaqar (since it is a non US software system for assisting in spacecraft operations planning) without an explicit license from the US State Department (or whatever department it is that issues such munitions licenses).

Oh well.

Planning trajectories is arguably neither manufacture or production of spacecraft, so it might be legal after all.

However with the anachronistic and conflicting laws we have I've grown resigned to the fact that essentially everybody that does anything on the internet is a criminal today.

Heaven help us if terrorists figure out the easy problem of how to push asteroids around and then someone gives them a way to calculate trajectories.

If terrorists get hold of the resources necessary to push asteroids around, they won't have any trouble planning the trajectories, ITAR or no ITAR...

-the other Doug

I'm reminded of the old Steve Martin skit: "You, too, can be a millionaire! It's easy: First, get a million dollars. Now..."

Just making a useless point, but using trajectory planning software for a study that leads to a mission is part of the manufacture process.

Not a useless point at all, Jim; seems to point directly to the rationale behind the apparent Catch-22 situation here.

Kepler's Laws are in the international public domain, obviously. Now, software to exploit them isn't, but irregardless it seems absurd to impose ITAR restrictions on orbit calculation software of any type...sadly, Jim's observation would appear to provide such justification.

VP, I do have an alternative suggestion: Touch bases with the amateur astronomy community. There are many serious ams out there now tracking asteroids & comets (the electronics revolution's impact has not been confined solely to improved image processing); in fact, it's a safe bet that many have written their own software for these applications. I'm certain that they'd be flattered as hell to talk to you & help you out given your position & credentials. One good place to start would be on the Sky & Telescope magazine pro-am collaboration site, http://skytonight.com/resources/proamcollab Good luck!

[EDIT] Actually, what am I thinking? You're in Tucson, right, which is pretty much the US capitol of amateur astronomy; you should be able to find someone local quite easily. Try http://www.tucsonastronomy.org/